DE19651550B4 - Semiconductor device and method for its production - Google Patents

Abstract

Semiconductor device, comprising:
a semiconductor substrate (1);
a transistor (Tr1 to Tr5) having a gate insulating film (5, 9 and 13), the transistor being formed in the semiconductor substrate;
a first plasma SiN film (24) disposed on the semiconductor substrate; and
a second plasma SiN film (25) coated on the first plasma SiN film;
wherein the first plasma SiN film (24) contains a smaller amount of hydrogen than the second plasma SiN film (25), and the first plasma SiN film (24) the passage of hydrogen from the second plasma SiN Movie (25) blocked.

Description

The The present invention relates to a semiconductor device IC (integrated circuit), which has a transistor with a Contains gate insulation film.

When a passivation film or an interlayer insulation film of a IC's were often one Silicon nitride film (SiN film) used.

US 5,160,998 describes a semiconductor device having two layers of SiN, for example, wherein the first layer applies a tensile stress and the second layer applies compressive stress to the layer in question. The first layer is formed as a tensile stress isolation layer by plasma CVD at a charge frequency of, for example, 13.56 megahertz, while the pressure stress isolation layer is formed by plasma CVD at a discharge frequency less than 2 megahertz (eg 200 kilohertz) at a processing temperature range of 200 to 450 ° C is generated.

US 4,365,264 describes the ratio of the hydrogen content in a SiN film to the internal stress, which occurs at very low hydrogen content as tensile stress, at higher hydrogen content than compressive stress. The described semiconductor device contains only one SiN layer.

In a transistor having a gate insulating film becomes a junction level of a gate insulating film shifted when hot carriers in the Enter gate insulation film. As a result, deterioration can occur the hot ones charge carrier take place so that the Gate insulation film not working properly.

If a plasma SiN film as, for example, a passivation film in one Transistor is used with a gate insulation film, the occurs hydrogen contained therein also in the gate insulating film and promotes the deterioration of the hot carriers (The Technical Studies Reports At The Electronic Data Communication Learned Society 90-123, Page 33, "Hot Carrier Effects "by Kenichiro TATSUUMA and others). If as a countermeasure against the problem described above is the amount of hydrogen in one Passivation film is reduced, the film tension of the passivation film increases. As a result, the problem arises that the formation of Al (aluminum) cavities and the like follows. The aluminum is here as a wiring used in a transistor. If, in addition, an attempt is made Reduce the film tension by increasing the gas flow rate to form a passivation film and thereby its thickness is reduced, the hiding power of the deteriorated Passivation film especially in a stepped range. In addition will the amount of hydrogen contained in the passivation film is likely increase. As a result, you can Problems related to the moisture resistance of the passivation film as well how the deterioration of the hot charge carriers occur. In this way it is impossible to achieve an improvement in the life of the hot charge carriers, and at the same time the properties of moisture resistance, a low film tension, the uniformity of the film thickness, which becomes important in the manufacture and manufacturability of the original one Design which for a protective film is necessary to sufficiently satisfy. If Further, the semiconductor device includes a memory device such as EPROM is, are the characteristics of UV transmission and the charge retention characteristic of a floating gate to important factors for the protective film.

Because of the above mentioned reasons is a semiconductor device required, which in excellent Measures the Life of the hot charge carrier elevated, while the characteristic of UV transmission and the charge retention characteristic as well as the moisture resistance (improved coverage of tiered areas) and decreased Film tension without a change the base film thickness is ensured. When such a semiconductor device should be realized, further, with respect to the conventional manufacturing method made change the film forming conditions do not cause a decrease in throughput and lead to an increase in manufacturing costs.

It is therefore an object of the present invention, a semiconductor device to disposal to put, which by a new construction in outstanding Measures her capacity maintains, and which is easy to manufacture.

The solution This object is achieved by the features of claims 1 and 10th

In A plasma SiN film has hydrogen (which is mainly composed of weak Si-H bonds are dissociated). It is said that in the case of a Short-channel MOS device of this hydrogen in the MOS device occurs to cause deterioration of the gate oxide film. For this reason, in the present invention, in terms of the Si-H bonds of the hydrogen contained in the plasma SiN film, When this film is formed, a first plasma SiN film with a reduced number of Si-H bonds and a second plasma SiN film with a larger number Si-H bonds are coated as the first plasma SiN film.

consequently although the hydrogen is ready for it, it is out of the second Plasma SiN film in the short channel MOS device side penetrate, this penetration of hydrogen through the first plasma SiN film blocked with a reduced amount of Si-H bonds (or the Hydrogen is trapped). (The reason is assumed that the Hydrogen from within the second plasma SiN film with the non-pair bonds of silicon in the first plasma SiN film with a reduced amount connects to Si-N bonds and thereby at the transition into the short-channel MOS device is prevented). This prevents adverse effects on the short channel MOS device (In particular, the deterioration of the gate oxide film is prevented). As a result, this structure is excellent in terms of the extension the life of the hot Charge carrier.

By The subsequent process can also easily produce a plasma SiN film a multilayer structure as described above. First, an ammonia gas and a gas from the linking group fed to the silanes, while the flow rate is increased by at least one of them, thereby forming a plasma SiN film with low hydrogen content (first plasma SiN film) form. Subsequently each of the two gases is fed at a fixed flow rate to thereby on the plasma SiN film with low hydrogen content to form a plasma SiN film (second plasma SiN film) whose Content of hydrogen higher is than that of the plasma SiN film with low hydrogen content.

If before flowing of the gas from the linking group of silanes, in a state in which nitrogen gas is allowed to flow, the voltage of a power source is applied, thereby by means of a plasma on the surface of an underneath lying layer on which the plasma SiN film with low Hydrogen content is deposited, a roughness processing the surface perform and subsequently the plasma SiN film with low hydrogen content is started To train it, the plasma SiN film with low hydrogen content can be fixed adhere to it.

If Further, when forming the plasma SiN film with low hydrogen content a plasma SiN film with low hydrogen content mainly from Nitrogen gas and a gas of the linking group of silanes formed it will be possible the Si-N bond in the plasma SiN film with low hydrogen content to consolidate. Further, after forming the plasma SiN film with low hydrogen content, the amount of supplied nitrogen gas is reduced and on the other hand, the amount of supplied ammonia gas elevated to thereby produce a high Si content plasma SiN film mainly from ammonia gas and a gas of the linking group of silanes form, it is possible a decrease in film tension and an improvement in uniformity in the plane with respect to the high-Si plasma SiN film to reach.

Further Advantages and features of the present invention are due to the description of embodiments as well as from the drawings.

It shows:

1 a vertical sectional view illustrating a semiconductor device according to a first embodiment of the present invention;

2 a sectional view illustrating a first step of a method of manufacturing the semiconductor device;

3 a sectional view illustrating a second step of the method for producing the semiconductor device;

4 a sectional view illustrating a third step of the method for producing the semiconductor device;

5 a sectional view illustrating a fourth step of the method for producing the semiconductor device;

6 a sectional view illustrating a fifth step of the method for producing the semiconductor device;

7 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by a plasma CVD method;

8th Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film to be compared is produced by the plasma CVD method;

9 Fig. 10 is a graphical diagram illustrating the device life measured in terms of the amount of Si-H bonds in the plasma SiN film;

10 a graphical diagram illustrating the period during which a MOS transistor deteriorates;

11 _{FIG. 4 is} a graphical diagram illustrating the relationship between V _G and I _{sub used to} illustrate the maximum value I _{submax of} the substrate _current ; _FIG .

12 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method;

13 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method;

14 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method;

15 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method;

16 a sectional view illustrating a state of formation of the plasma SiN film;

17 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method according to a second embodiment of the present invention;

18 Fig. 12 is a diagram illustrating the respective states of gas supply, pressure and RF power when the plasma SiN film is produced by the plasma CVD method;

19 a sectional view illustrating a main portion of a semiconductor device according to a third embodiment of the present invention; and

20 10 is a sectional view illustrating a main portion of a semiconductor device according to a fourth embodiment of the present invention.

First embodiment

Under Referring now to the drawings, a first embodiment will be described of the present invention.

1 FIG. 15 is a vertical sectional view illustrating a semiconductor device according to the first embodiment. FIG. This device embodies an IC (Integrated Circuit) for use in a motor vehicle and includes a MOS transistor.

The Operating environment (especially the temperature environment) for one Automotive IC is rough. Consequently, the required performance characteristic such that when Carry out an inverter operation at one frequency of 20 MHz, at an applied voltage Vd of -5.5 V and an employment relationship from 50% of the time at which the operating speed of the MOS transistor decreases by 10%, the value of 1.7 years is sufficient, which for a DC load voltage Vd = 5.5 V estimated assuming a warranty period for a motor vehicle of 19 years (so that the Automotive IC its regular use while survives a period of 19 years).

It It should be noted that the Construction of this semiconductor device for EPROM or EEPROM (including a Flash Memory) can be used.

A silicon substrate 1 P-type serves as a semiconductor substrate. In the silicon substrate 1 the P-type becomes a P-well region 2 and an N-well area 3 educated. In a surface area of the P-well area 2 in the silicon substrate 1 of the P-type, an N-channel MOS transistor Tr1 and an N-channel MOS transistor Tr2 are formed. In a surface area of the silicon substrate 1 Also, an N-channel MOS transistor Tr3 is formed by the P-type. Further, in a surface region of the N-well region 3 in the silicon substrate 1 formed of P-type P-channel MOS transistor Tr4 and a P-channel MOS transistor Tr5.

To explain a detailed construction of the MOS transistors Tr1 to Tr5, field oxide films 4 (LOCOS oxide films) on the surface portion of the silicon substrate 1 formed of P-type. In the region where the N-channel MOS transistors Tr1 and Tr2 are formed, the surface area of the silicon substrate is formed 1 P-type on gate oxide films 5 on which polysilicon gate electrodes 8th be formed. In the areas of the P-well area 2 located below the polysilicon gate electrodes 8th become N ⁺ source areas 6 and N ⁺ sink areas 7 educated.

In the region where the N-channel MOS transistor Tr3 is formed, the surface area of the silicon substrate is formed 1 P-type on a gate oxide film 9 on which a polysilicon gate electrode 12 is trained. The area of the silicon substrate 1 P-type, which extends below the polysilicon gate electrode 12 is therein forms an N ⁺ source area 10 and an N ⁺ sink area 11 out.

In the region in which the P-channel MOS transistors Tr4 and Tr5 are formed, the surface area of the silicon substrate is formed 1 P-type on gate oxide films 13 on which polysilicon gate electrodes 16 be formed. The areas of the N-well area 3 located below the polysilicon gate electrodes 16 are P ⁺ source areas 14 and P ⁺ sink areas 15 , Here, the thickness of each of the gate oxide films is 5 . 9 and 13 about 200 Å.

Over the silicon substrate 1 P-type MOS transistors Tr1 to Tr5 is a BPSG film 17 formed over which first aluminum wiring layers 18a . 18b and 18c are formed. The first wiring layer 18a and the N ⁺ source area 6 of the N-channel MOS transistor Tr1 are electrically connected to each other through a contact hole. About the BPSG movie 17 and the surfaces of the first aluminum wiring layer 18a . 18b and 18c becomes a plasma SiN film 19 formed with a thickness of 1000 Å. Above the plasma SiN film 19 becomes a TEOS (tetraethyl orthosilicate) film 20 formed, which serves as a first interlayer insulating film. In specific areas of the TEOS film 20 are SOG (Spin On Glass) films 21 designed to smooth its surface.

About the TEOS movie 20 and the surfaces of the SOG films 21 becomes a TEOS movie 22 formed, which serves as a second interlayer insulating film. About the TEOS movie 22 become second aluminum wiring layers (multilayer wiring) 23a and 23b educated. The second aluminum wiring layer 23b and the first aluminum wiring layer 18c are electrically connected to each other via a contact hole. Using a multi-layer aluminum wiring (second aluminum wiring layers 23a and 23b and first aluminum wiring layers 18a . 18b and 18c , etc.) are the voltage of a power source and a ground voltage to the MOS transistors Tr1 to Tr5, which in the silicon substrate 1 P-type formed, created.

About the TEOS movie 22 and the surfaces of the second aluminum wiring layers 23a and 23b becomes a plasma SiN film 24 formed with a low hydrogen content, above which a plasma SiN film 25 is formed with a high hydrogen content. The plasma SiN film 24 with a low hydrogen content contains less hydrogen than the plasma SiN film 25 with a high hydrogen content. Specifically, the amount of Si-H bonds in the plasma SiN film is 25 with high hydrogen content 8 × 10 ²¹ / cm ³ , and on the other hand, the content of Si-H bonds in the SiN film 24 with a low hydrogen content 6 × 10 ²¹ / cm ³ or less. The total thickness of the plasma SiN films 24 and 25 is about 16,000 Å. The thickness of the plasma SiN film 24 with a low hydrogen content is about 500 Å.

Here, the plasma SiN film has 25 with a high hydrogen content, a low film tension and thereby a good coverage characteristic for levels (the ability to cover a stepped area). The plasma SiN film 25 However, with a high hydrogen content contains a lot of hydrogen in itself. The hydrogen becomes a factor which causes deterioration of the hot carriers in the MOS transistors Tr1 to Tr5 present in the silicon substrate 1 are formed of the P-type caused. The plasma SiN film 24 having a low hydrogen content has the property of preventing the passage of hydrogen.

While the hydrogen is ready from within the plasma SiN film 25 With the high hydrogen content used as a passivation film, it allows the use of the plasma SiN films 24 and 25 with such a two-layer structure, the hydrogen through the plasma SiN film 24 with a low hydrogen content, which has a reduced amount of Si-H bonds to block (capture). It is believed that this phenomenon takes place in that the hydrogen which flows from within the plasma SiN film 25 With a high hydrogen content has gone out, with the non-pair bonds of silicon in the plasma SiN film 24 with a low hydrogen content. As a result, the hydrogen is prevented from passing to the side of the MOS transistors Tr1 to Tr5.

Next, the method for manufacturing the above-constructed IC for a motor vehicle will be described with reference to FIGS 2 to 6 explained.

As in 2 illustrates a silicon substrate 1 made of P-type. Then it becomes the P-well area 2 and the N-well area 3 educated. Using a LO COS oxidation processes become on the surface area of the silicon substrate 1 P-type field oxide films 4 and gate oxide films 5 . 9 and 13 educated.

Subsequently, as in 3 illustrates polysilicon gate electrodes 8th . 12 and 16 on the gate oxide films 5 . 9 and 13 educated. Further, as in 4 illustrates source area 6 . 10 and 14 and sink areas 7 . 11 and 15 formed by an ion implantation method.

Then be like in 5 illustrated above the silicon substrate 1 P-type one after the other a BPSG movie 17 , first aluminum wiring layers 18a . 18b and 18c , a plasma SiN film 19 , a TEOS movie 20 , a SOG movie 21 , a TEOS movie 22 and second aluminum wiring layers 23a and 23b educated.

Subsequently, as in 6 illustrates a plasma SiN film using a plasma CVD method 24 formed with low-hydrogen content. As in 1 further illustrated thereon is a plasma SiN film 25 formed with a high hydrogen content. Subsequently, special areas of the plasma SiN films 24 and 25 etched and thereby opened to provide aluminum pads.

Now, the process of coating a plasma SiN film will be described 24 with a low hydrogen content and a plasma SiN film 25 explained in detail with a high hydrogen content.

In this embodiment is used as a plasma CVD apparatus described by Nippon A · S · M Co. Ltd. manufactured EAGLE-10 used. This device is a single layer plasma CVD device.

In 7 For example, the respective states of supplying the RF power, the change in pressure, the supply of nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ), and the supply of silane gas (SiH ₄ ) are illustrated when this plasma CVD apparatus is operated ,

In 7 First, the pressure reduction operation and the supply of nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ) are started simultaneously. To obtain a vacuum target value (4.3 Torr), a period of 15 seconds is required as the pressure reduction period. Nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ) can also reach the corresponding target flow rates (N ₂ : 1200 sccm, NH ₃ : 1800 sccm) after 10 seconds. When the target value of the vacuum and the target gas flow rates have been reached, the high-frequency voltage of a power source (RF power) is applied between a lower electrode and an upper electrode (high voltage or high 485 W and low voltage 215 W). Five seconds after switching on, the supply of silane gas (SiH ₄ ) is started. At this time, the film formation begins. The supply of silane gas (SiH ₄ ) is increased linearly for 5 seconds. During this period of 5 seconds will be a like in 1 indicated plasma SiN film 24 formed with low hydrogen content. After the flow rate of silane gas (SiH ₄ ) has reached a predetermined value (150 sccm), its feeding is continued at a fixed flow rate. As a result, a plasma SiN film is formed 25 out 1 formed with a high hydrogen content.

The method according to the first embodiment, which in 7 is now illustrated in comparison with the in 8th which is used when forming a conventional single-layered plasma SiN film is explained. In the training of in 8th In the illustrated single layer film, the pressure reduction operation and the supply of nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ) are started simultaneously. When the target value of the vacuum and the supply of nitrogen gas and ammonia gas at the respective fixed flow rates have been reached, the supply of silane gas is started. After the silane gas has been fed at a fixed flow rate, the RF power is turned on to start film formation. The film is continuously deposited until its thickness reaches a predetermined thickness.

As if comparing the views of the 7 and 8th is clear, due to the change in the timing at which the supply of silane gas increases, the plasma SiN film formed in the initial stage of film formation and the plasma SiN film formed when silane gas is continuously supplied , different from each other in terms of properties. In the in 7 In the illustrated case, this means that the timing of turning on the RF power is set before the start of the supply of silane gas (SiH ₄ ). When supplying silane gas, whereby its flow rate is increased, and since the pressure has been reduced to 4.3 Torr and discharge can be performed by the RF power, it becomes possible to form a plasma SiN film 24 form with low hydrogen content.

9 FIG. 16 illustrates the degradation period of a MOS transistor measured with respect to the amount of Si-H bonds in FIG Plasma SiN film. In 9 the amount of Si-H bonds is plotted on the abscissa, and the time Gm 10% at which the characteristic of the MOS transistor decreases by 10% was plotted on the ordinate. The operating voltage is set to 5.5 volts. As a sample, an N-channel MOS transistor constructed such that W (gate width) / L (gate length) = 25.0 / 1.0 is also used.

From the relationship between the amount of Si-H bonds and the deterioration period of the MOS transistor in FIG 9 It can be seen that it is necessary that the amount of Si-H bonds in a low-hydrogen plasma SiN film be 6 × 10 ²¹ / cm ³ or less to survive continuous use for 1.7 years.

10 FIG. 14 illustrates the measured deterioration period during which the characteristics of the MOS transistor decrease by 10% both in the case of this embodiment (the two-layer plasma SiN film) and the case of the comparative example (the one-layer plasma SiN film). In 10 _{For example} , the maximum value I _submax / W of the sink current per unit of the gate width is plotted on the abscissa in a MOS transistor, and the time Gm 10% is plotted on the ordinate. Also used as samples are N-channel MOS transistors constructed such that W / L = 25.0 / 1.0. Here, I _{submax represents} a maximum value of a substrate _current . As in 11 1, the maximum value I _{submax of} the substrate _{current is} a value I _{sub of} the substrate current corresponding to a maximum value of the substrate current in the relationship between a gate voltage V _G and the substrate current I _sub .

Out 10 As can be seen, the use of the single-layer plasma SiN film, which is a conventional product, could not meet the requirements of continuous use for 1.7 years when the operating voltage is set to 5.5 volts. As in 10 however, the use of the two-layered plasma SiN film according to the apparatus of the first embodiment could satisfy the same requirements.

• (a) Der Plasma-SiN-Film, welcher als ein Passivierungsfilm (Oberflächenschutzfilm) wirkt, wird in einer zweilagigen Struktur ausgebildet. Die untere Schicht wird als der Plasma-SiN-Film mit niedrigem Wasserstoffgehalt ausgebildet, welcher hinsichtlich des Gehalts an Wasserstoff geringer ist als der Plasma-SiN-Film der oberen Schicht. Als Folge davon ist es möglich, den Wasserstoff im Plasma-SiN-Film der oberen Schicht daran zu hindern, in die MOS-Transistorseite einzudringen. Folglich ist die Lebensdauer der heißen Ladungsträger gesichert, das heißt, der Verschlechterungszeitraum des MOS-Transistors ist sicherlich lange genug.
• (b) Als das Verfahren zur Herstellung des Plasma-SiN-Films mit einer Zweischichtstruktur mit dem Plasma-SiN-Film mit niedrigem Wasserstoffgehalt und dem Plasma-SiN-Film mit hohem Wasserstoffgehalt wurden die beiden folgenden Verfahrensarten angewendet. In einem Zustand, in dem das Ammoniakgas mit einer festen Fließ geschwindigkeit zugeführt wird, wird nämlich die Zuführung des Gases aus der Verbindungsgruppe der Silane so durchgeführt, daß dessen Fließgeschwindigkeit erhöht wird. Als Folge davon wird ein Plasma-SiN-Film 24 mit niedrigem Wasserstoffgehalt ausgebildet. Bei der anderen Verfahrensart wird die Zuführung von Ammoniakgas und dem Gas aus der Verbindungsgruppe der Silane bei einer festen Fließgeschwindigkeit durchgeführt. Aufgrund der Zuführung wird auf einem Plasma-SiN-Film 24 mit niedrigem Wasserstoffgehalt ein Plasma-SiN-Film 25 mit hohem Wasserstoffgehalt, dessen Wasserstoffgehalt höher ist als der des Plasma-SiN-Films 24 mit niedrigem Wasserstoffgehalt, ausgebildet. Folglich kann durch die kontinuierliche Verwendung derselben Vorrichtung der Plasma-SiN-Film mit Zweischichtstruktur, welcher als der Passivierungsfilm wirkt, ausgebildet werden.

As mentioned above, the present embodiment has the following two characterizing properties (a) and (b):

• (a) The plasma SiN film, which functions as a passivation film (surface protection film), is formed in a two-layered structure. The lower layer is formed as the low-hydrogen plasma SiN film which is lower in hydrogen content than the upper-layer plasma SiN film. As a result, it is possible to prevent the hydrogen in the plasma SiN film of the upper layer from entering the MOS transistor side. Consequently, the life of the hot carriers is ensured, that is, the deterioration period of the MOS transistor is certainly long enough.
• (b) As the method of producing the plasma SiN film having a two-layer structure with the low-hydrogen plasma SiN film and the high-hydrogen plasma SiN film, the following two kinds of methods were adopted. Namely, in a state in which the ammonia gas is supplied at a fixed flow rate, the supply of the gas from the linking group of the silanes is carried out so that its flow rate is increased. As a result, a plasma SiN film is formed 24 formed with low hydrogen content. In the other mode, the supply of ammonia gas and the gas from the linking group of silanes is carried out at a fixed flow rate. Due to the feed is on a plasma SiN film 24 low-hydrogen content, a plasma SiN film 25 high hydrogen content whose hydrogen content is higher than that of the plasma SiN film 24 with low hydrogen content, formed. Thus, by the continuous use of the same device, the plasma SiN film having a two-layer structure which functions as the passivation film can be formed.

When next Modifications of the first embodiment will be explained.

In 7 For example, the flow rate at which silane gas (SiH ₄ ) is supplied is linearly increased. As in 12 However, when feeding silane gas, its flow rate can be increased in a non-linear manner but curvilinearly (in FIG 12 are shown by a dashed line and a solid line two examples).

Or as in 13 For example, when the silane gas is supplied, its flow rate may be increased in the form of a staircase (stepwise) (in FIG 13 a solid line indicates a three-step operation in increasing the silane gas, and a chain line indicates a two-step operation).

Or as in 14 For example, as the silane gas is supplied, its flow rate may be increased in such a manner that it is lowered for certain periods of time.

Or as in 15 can be illustrated after switching on the high-frequency power source, the flow rate of the silane gas may be increased during a period in which the flow rates of nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ) are increased to thereby form a plasma SiN film 24 form with low hydrogen content.

Second embodiment

When next becomes a second embodiment of the present invention paying attention to the difference from the first embodiment is directed.

In the manufacturing method according to the first embodiment, after forming the plasma SiN film 24 with low hydrogen content and the plasma SiN film 25 high hydrogen content etching of the plasma SiN films 24 and 25 performed so as to open the aluminum pad areas. As in 16 however, at this time, the plasma SiN film is illustrated 24 low hydrogen content on the aluminum wiring 23b easily detached from this. Since the etching solution penetrates in this region of the defective adhesion, it is difficult to obtain an opening area of a desired configuration. That is, when comparing the etching rate of a plasma SiN film containing a large amount of hydrogen with that of a plasma SiN film containing a small amount of hydrogen, the etching speed of the latter plasma SiN film is higher , In plasma SiN film 24 low hydrogen content which is in contact with the aluminum wiring 23b Therefore, as the underlying layer, the etching solution quickly comes out of the region of improper adhesion, with the result that there is an inconvenient side etching.

As in 17 For this reason, in the second embodiment, prior to flowing the silane gas (SiH ₄ ), it is exemplified that the RF power (high-frequency power source voltage) is applied in a state in which nitrogen gas (N ₂ ) flows. As a result, with respect to the surface of the aluminum wiring 23b performed a plasma surface roughening process. Subsequently, the film formation of the plasma SiN film 24 started with low hydrogen content.

Specifically, nitrogen gas (N ₂ ) and ammonia gas (NH ₃ ) are first started to be simultaneously supplied. After 5 seconds, their flow rates are set to predetermined values (N ₂ : 2900 sccm, NH ₃ : 300 sccm). After another 5 seconds, the RF power is turned on for 10 seconds. As a result of this pre-plasma processing, nitrogen gas (N ₂ ) passes into a plasma. As a result, the surface of the aluminum wiring becomes 23b showing the underlying layer of the plasma SiN film 24 with low hydrogen content, tapped by the plasma to form irregularities on it.

20 seconds after the pre-plasma processing is completed, the RF power is applied (High Voltage or High 485 W and Low Voltage or Low 215 W). 3 seconds after the RF power is turned on, the supply of silane gas (SiH ₄ ) is started, and thereby film formation is started. And, by increasing the flow rate of the silane gas supply (SiH ₄ ), the plasma SiN film becomes 24 formed with low hydrogen content. 5 seconds after the start of feeding silane gas, the flow rate of the silane gas (SiH ₄ ) is set to a predetermined value (150 sccm). Then, after another 5 seconds, the flow rate of nitrogen gas (N ₂ ) is lowered, and the flow rate of ammonia gas (NH ₃ ) is increased. 5 seconds after the changes in the flow rates of nitrogen gas and ammonia gas, the flow rate of the nitrogen gas (N ₂ ) and the flow rate of the ammonia gas (NH ₃ ) are set to 1200 sccm and 1800 sccm, respectively. In this state becomes a plasma SiN film 25 high hydrogen content on the plasma SiN film 24 coated with low hydrogen content.

In 17 This is the reason for supplying a large amount of nitrogen in the formation of a plasma SiN film 24 with low hydrogen content, ie, when silane gas increases (its flow rate is increased stepwise), the strengthening of Si and N bonding. Comparing the production of the SiN film from nitrogen into ammonia gas with the production of the SiN film from nitrogen into nitrogen gas That is, the bonding of Si and N in the SiN film formed of nitrogen in nitrogen gas is stronger than that in the plasma SiN film formed of nitrogen in ammonia gas. However, when the SiN film of nitrogen was formed in nitrogen gas, this film has an increased film stress or has inferior in-plane uniformity. Therefore, when the supply of silane gas was stabilized, the flow rate of nitrogen gas was lowered and the flow rate of ammonia gas was increased to thereby form a plasma SiN film 25 having a high hydrogen content, which has a low film stress and excellent in-plane uniformity.

It It should be noted that the Nitrogen gas in the plasma CVD process originally acts as a carrier gas.

• (a) Vor dem Fließenlassen des Gases aus der Verbindungsgruppe der Silane wird die Spannung einer Energiequelle in einem Zustand angelegt, in welchem Stickstoffgas zugeführt wird. Hinsichtlich der Oberfläche der darunterliegenden Schicht wird folglich eine Plasma-Oberflächenaufrauhungsbearbeitung durchgeführt. Da die Filmbildung danach gestartet wird, wird auf der aufgerauhten Oberfläche der darunter liegenden Schicht ein Plasma-SiN-Film 24 mit einem niedrigen Wasserstoffgehalt ausgebildet. Der Plasma-SiN-Film 24 mit niedrigem Wasserstoffgehalt kann daher fest auf diese darunterliegende Schicht gehaftet werden. Das heißt, die Oberfläche der Al-(Aluminium)-Schicht, welche als die darunter liegende Schicht fungiert, wird durch das Plasma geklopft und dadurch in einen unregelmäßigen Zustand gebracht. Als Folge davon wird die Haftung zwischen dem Plasma-SiN-Film 24, welcher eine geringe Menge an Wasserstoff enthält, und der Aluminiumverdrahtung 23b verstärkt. Aufgrund der Durchführung der Vorplasmabearbeitung steigt ebenfalls die Temperatur des Substrates. Als Folge davon erreicht die Substrattemperatur ungefähr die Temperatur des Plasma-SiN-Films 24 mit niedrigem Wasserstoffgehalt, welche sich einstellt, wenn der Plasma-SiN-Film 24 gebildet wird, wodurch die Haftung verstärkt wird.
• (b) Bei der Ausbildung eines Plasma-SiN-Films 24 mit niedrigem Wasserstoffgehalt wird eine große Menge an Stickstoffgas zugeführt, um den Plasma-SiN-Film 24 hauptsächlich aus Stickstoff in Stickstoffgas zu bilden. Dadurch ist es möglich, die Bindung zwischen Si und H im Plasma-SiN-Film 24 mit niedrigem Wasserstoffgehalt zu festigen. Nach der Ausbildung des Plasma-SiN-Films 24 mit niedrigem Wasserstoffgehalt wird die Fließgeschwindigkeit von Stickstoffgas verringert und die Fließgeschwindigkeit von Ammoniakgas erhöht. Es ist somit möglich, die Abnahme der Filmspannung und die Zunahme der Gleichförmigkeit innerhalb der Ebene im Hinblick auf den Plasma-SiN-Film 25 mit hohem Wasserstoffgehalt zu erreichen.

As mentioned above, the present embodiment has the following two characterizing properties (a) and (b):

• (a) Before flowing the gas out of the linking group of silanes, the voltage of a power source is applied in a state in which nitrogen gas is supplied. As for the surface of the underlying layer, therefore, plasma surface roughening processing is performed. Thereafter, since the film formation is started, a roughened surface of the underlying layer becomes a plasma SiN film 24 formed with a low hydrogen content. The plasma SiN film 24 low hydrogen content can therefore be firmly adhered to this underlying layer. That is, the surface of the Al (aluminum) layer, which functions as the underlying layer, is tapped by the plasma and thereby brought into an irregular state. As a result, the adhesion between the plasma SiN film becomes 24 containing a small amount of hydrogen and the aluminum wiring 23b strengthened. Due to the performance of Vorplasmabearbeitung also increases the temperature of the substrate. As a result, the substrate temperature reaches approximately the temperature of the plasma SiN film 24 with low hydrogen content, which sets when the plasma SiN film 24 is formed, whereby the liability is increased.
• (b) When forming a plasma SiN film 24 With a low hydrogen content, a large amount of nitrogen gas is supplied to the plasma SiN film 24 mainly nitrogen in nitrogen gas. This makes it possible to bond Si and H in the plasma SiN film 24 with low hydrogen content. After the formation of the plasma SiN film 24 With low hydrogen content, the flow rate of nitrogen gas is reduced and the flow rate of ammonia gas is increased. It is thus possible to reduce the film tension and increase the in-plane uniformity with respect to the plasma SiN film 25 to achieve high hydrogen content.

By the way, in 17 Once the pre-plasma has been processed, the RF power is switched off once. However, this switching off is not always necessary. If the RF power is left on for a long time, the irregularities of the underlying layer (aluminum wiring) become too large. For this reason, the duration of the pre-plasma processing is set so that a predetermined period of time is not exceeded.

When next Modifications of the second embodiment will be explained.

As in 18 Illustratively, after performing pre-plasma processing while supplying nitrogen gas (N ₂ ), it is possible to start feeding ammonia gas (NH ₃ ).

It should be noted that although both in the first and the second embodiment, such as in the 7 and 17 It is also possible to set the concentrations of gases within a chamber of the CVD apparatus, the amounts (flow rates) of supplied gases being fixed. Since the concentration of gas becomes low, when its flow rate is low, and becomes high when its flow rate is high, it means that the semiconductor device can be manufactured by adjusting the concentration of the gas so that the concentration of the gas within the Chamber reached a predetermined value.

Third embodiment

When next becomes a third embodiment of the present invention, paying attention to the difference to the first embodiment is directed.

In the first embodiment, the two-layer structure was applied to the plasma SiN film, which functions as the passivation film. In the third embodiment, the plasma SiN film having the two-layer structure is applied to both a passivation film and an interlayer insulating film. That is, the plasma SiN film having the two-layer structure is also applied to the plasma SiN film 19 of in 1 used ICs shown. The third embodiment will now be described with reference to FIG 19 , which is an enlarged view of the area of 1 is in which the N-channel MOS transistor Tr3 is formed, explained.

According to the third embodiment, on a plasma SiN film 30 with a low hydrogen content, a plasma SiN film 31 coated with a high hydrogen content. The total thickness of the plasma SiN film 30 with low hydrogen content and the plasma SiN film 31 with high hydrogen content is about 1000 Å. The thickness of the plasma SiN film 30 with low hydrogen content is about 160 Å. The remaining portions are the same as those shown in the first embodiment, and those portions designated by the same reference numeral will be omitted in detail.

The one in the TEOS films 20 and 22 or the SOG movie 21 contained hydrogen becomes the cause of the deterioration of the hot carriers in the MOS transistor, which in the silicon substrate 1 is formed of P-type. The plasma SiN film 31 Hydrogen containing high hydrogen also becomes the cause of the deterioration of the hot carriers in the MOS transistor. The plasma SiN film 30 with low hydrogen content prevents the passage of hydrogen. As a result of this, although hydrogen is being emitted from within the films 20 . 22 and 31 is ready for the penetration into the MOS transistor side, the entry of hydrogen through the plasma SiN film 30 with a low hydrogen content and a reduced number of Si-H bonds blocked (the hydrogen is trapped).

By applying the two-layer structure to the plasma SiN film 19 which acts as an interlayer insulating film as mentioned above, excellent protection of the performance of the MOS transistor is achieved. Further, as claimed in connection with the first embodiment, the production of the plasma SiN film having the two-layer structure is simple.

Fourth embodiment

When next becomes a fourth embodiment of the present invention, paying attention to the difference to the third embodiment is directed.

In the third embodiment, a plasma SiN film 19 as the interlayer insulating film, which is between the first aluminum wirings 18a . 18b and 18c and the second aluminum wirings 23a and 23b is arranged, used. That is, the two-layer structure is applied to the plasma SiN film 19 applied, which is arranged between the multilayer wiring. In the fourth embodiment, the plasma SiN film is used as an insulating film disposed between a MOS transistor and a wiring disposed on the MOS transistor. That is, the fourth embodiment uses the plasma SiN film as a substitute for the BPSG film 17 in the 1 illustrated IC.

The fourth embodiment will now be described with reference to FIG 20 (which is an enlarged view of the area of 1 represents, in which the N-channel MOS transistor Tr3 is formed), which in turn on 19 relates explained.

Over a gate electrode 21 of an N-channel MOS transistor Tr3 becomes a plasma SiN film 40 formed with a low hydrogen content. On the plasma SiN film 40 low hydrogen content becomes a plasma SiN film 41 coated with high hydrogen content. About these plasma SiN films 40 and 41 becomes an aluminum wiring 18a . 18b and 18c educated. The remaining portions are the same as those listed in the third embodiment, and the portions designated by the same reference numerals will be omitted in detail.

Also in this embodiment, the plasma SiN film 41 hydrogen containing high hydrogen content causes the deterioration of the hot carriers in the MOS transistor formed in the P-type silicon substrate. The plasma SiN film 40 with low hydrogen content prevents the passage of hydrogen. As a result, although hydrogen from within the plasma SiN film 41 high hydrogen content is available for penetration into the MOS transistor, the penetration of this hydrogen through the plasma SiN film 40 with low hydrogen content and a reduced amount of Si-H bonds blocked (the hydrogen is trapped).

The The present invention is not limited to the above-mentioned embodiments. The is called, the present invention can be applied to only the plasma SiN film, which serves as the interlayer insulating film or only on the plasma SiN film which can be used as the insulating film covering the gate electrode of the MOS transistor, be applied. This means, the present invention can be applied to only the interlayer insulating film or on only the insulating film, which between the MOS transistor and the wiring arranged thereon is applied be without the Invention on the passivation film, which is the surface protection film is, is applied.

The The present invention can also be applied to a semiconductor device how an IGBT and an LDMOS are applied.

Further the present invention is not that in a motor vehicle limited IC used, but can also go to an IC for another use will be applied.

Claims (20)

A semiconductor device, comprising: a semiconductor substrate ( 1 ); a transistor (Tr1 to Tr5), which has a gate insulation film ( 5 . 9 and 13 ), wherein the transistor is formed in the semiconductor substrate; a first plasma SiN film disposed on the semiconductor substrate ( 24 ); and a second plasma SiN film coated on the first plasma SiN film ( 25 ), wherein the first plasma SiN film ( 24 ) contains a smaller amount of hydrogen than the second plasma SiN film ( 25 ), and the first plasma SiN film ( 24 ) the passage of hydrogen from the second plasma SiN film ( 25 ) blocked. Semiconductor device according to Claim 1, characterized in that the first plasma SiN film ( 24 ) has an amount of Si-H bonds of 6 × 10 ²¹ / cm ³ or less. A semiconductor device according to claim 1, characterized in that said first and second plasma SiN films ( 24 and 25 ) can be used as a surface protection film. A semiconductor device according to claim 1, further comprising: a multilayer wiring ( 18a . 18b . 18c . 23a and 23b ) for applying electrical energy to the transistor, the first and second plasma SiN films ( 30 and 31 ) may be used as an interlayer insulating film disposed between the multilayer wiring. Semiconductor device according to Claim 4, characterized in that the multilayer wiring ( 18a . 18b . 18c . 23a and 23b ) is made of aluminum. A semiconductor device according to claim 1, further comprising: a wiring (FIG. 18c ) for applying electrical energy to the transistor, the first and second plasma SiN films ( 40 and 41 ) may be used as an insulating film disposed between the transistor and the wiring. Semiconductor device according to Claim 6, characterized in that the wiring ( 18c ) is made of aluminum. Semiconductor device according to Claim 1, characterized in that the first plasma SiN film ( 24 ) is thinner than the second plasma SiN film ( 25 ). Semiconductor device according to Claim 1, characterized in that the first plasma SiN film ( 24 ) is formed mainly of nitrogen gas and silane gas, and the second plasma SiN film ( 25 ) is formed mainly of ammonia gas and silane gas. Method for producing a semiconductor device in which a transistor (Tr1 to Tr5) is provided with a gate insulation film ( 5 . 9 and 13 ) in a semiconductor substrate ( 1 ) whose surface is coated with a plasma SiN film ( 24 and 25 ), which is formed by a plasma CVD method, which is directed to the formation of a SiN film on the semiconductor substrate during the supply of ammonia gas and a gas from the silane linking group, the method comprising the steps of: Forming a low-Si content plasma SiN film by supplying the ammonia gas and the silane linking group gas while increasing at least one of the gas amounts of ammonia and the silanes linking group gas; and coating a plasma SiN film on the low-hydrogen plasma SiN film containing plasma-SiN film coated with more hydrogen than the low-hydrogen plasma SiN film by exposing the ammonia gas and the gas of the silane linking group be fed at a fixed flow rate. Method for producing a semiconductor device according to claim 10, characterized in that the step of forming of the plasma SiN film with low hydrogen content under one reduced pressure is performed in a state in which an electric Discharge possible is. Method for producing a semiconductor device according to claim 10, characterized in that the step of forming of the plasma SiN film with low hydrogen content in one state carried out in which the ammonia gas flows at a fixed flow rate supplied and the gas from the linking group of silanes increasing its flow rate supplied becomes. Method for producing a semiconductor device according to claim 10, characterized in that the step of forming of the plasma SiN film with low hydrogen content in a manner carried out in which the ammonia gas and the silane gas are supplied, where at least one of the flow rates is increased linearly by the ammonia gas or the silane gas. Method for producing a semiconductor device according to claim 10, characterized in that the step of forming of the plasma SiN film with low hydrogen content in a manner carried out in which the ammonia gas and the silane gas are supplied, the flow rate of silane gas gradually increased becomes. Method for producing a semiconductor A device according to claim 10, characterized in that the step of forming the low-hydrogen plasma SiN film regulates the flow rates of the ammonia gas and the silane gas such that the low-Si plasma plasma SiN film has an amount of Si-H bonds of 6 × 10 ²¹ / cm ³ or less. Method for producing a semiconductor device according to claim 10, characterized in that in the step of forming The plasma SiN film with a low hydrogen content in a larger amount feeds to nitrogen gas is supplied as that in the coating step. Method for producing a semiconductor device according to claim 16, characterized in that in the step of forming of the low-Si plasma SiN film has a lower Amount of ammonia gas supplies is supplied as that in the coating step. Method for producing a semiconductor device according to claim 10, further comprising the step: Applying a voltage a power source in a state in which nitrogen gas is supplied, before the gas from the linking group of silanes through the step the forming flowed is to use a plasma of nitrogen on a surface of a underlying layer on which the plasma SiN film with low Hydrogen content is formed, a surface roughening processing perform. Method for producing a semiconductor device according to claim 18, characterized in that the step of forming The plasma SiN film with a low hydrogen content in a larger amount feeds the nitrogen gas as that supplied in the step of coating. Method for producing a semiconductor device according to claim 19, characterized in that the step of forming of the low-Si plasma SiN film has a lower Supply quantity of ammonia gas as that supplied in the step of coating.